Electron distribution of small Ni particles and Ce ions in X and Y zeolites related to their catalytic properties

Catalytic behaviour of nickel particles smaller than 1.3 nm, encaged in X and Y zeolites, in the presence of Ce³⁺, is related to their electronic properties. In general the rates of reaction are lower than those of a standard catalyst made of 2.5 nm nickel particles on SiO₂; this is attributed to the strong localization of the Ni 3d states due to the size effect. However a high rate, more than twice the standard, is found for Ni in X zeolite, in relation with a Ni 3d ¹⁰ configuration. On the other hand the fragmentation of butane is deeper with Ni in Y support than in X support and this corresponds to a high density of Nid states at the Fermi level.